Quick answer
A broker API is a documented interface that lets software request market data or interact with an account. It may support read-only data, order submission, account management or some combination. API access does not guarantee low latency, a particular fill, a stable connection or permission to use every product; check the broker’s documentation, account terms, authentication rules and rate limits.
Key takeaways
- Separate market-data access from account and order permissions.
- REST, WebSocket and FIX serve different communication patterns; provider support varies.
- An API token is sensitive account access. Store it securely and grant only necessary permissions.
- Test in a practice environment, but do not assume practice fills match live execution.
- Confirm entity, product, rate limits, fees, outage behavior and support terms.
What Is a Broker API?
An application programming interface (API) is a documented way for one program to request services or data from another. A broker API may expose prices, account balances, positions, order creation or order management. The word “API” alone does not reveal which permissions are available.
The API is part of the broker’s service, not a separate licence or guarantee. Identify the legal company that holds the account, the products exposed through the interface and the terms that govern automated access.
Common API Types and Uses
| REST / HTTP | Request-response calls are often used for account queries, configuration and order operations. Rate limits and request semantics are provider-specific. |
|---|---|
| WebSocket / streaming | A persistent connection can deliver live updates or price streams. Reconnection, heartbeat, message limits and data entitlements need checking. |
| FIX | A widely used messaging standard for financial-market communication. Access, supported message types and commercial arrangements depend on the broker and venue. |
| Market-data API | May be read-only and subject to exchange, redistribution or non-professional data terms; it may not allow trading. |
Authentication, Permissions and Security
Read the broker’s authentication guide and distinguish a login session from an API key or token. Use separate credentials where supported, restrict permissions to the minimum needed, rotate or revoke credentials when exposure is suspected, and never put secret keys in a public repository, browser bundle, screenshot or log.
Protect the system that stores credentials with access controls, encryption in transit and at rest, monitoring and a documented incident response. A broker’s API authentication does not replace the user’s responsibility to secure the application.
Orders, State and Failure Handling
Before using an API for trading, understand how the provider accepts, rejects, modifies and confirms orders. A successful HTTP response can acknowledge a request without proving a final fill. Use the provider’s order identifiers, reconcile open orders and positions, and make retries safe so that a timeout does not accidentally submit a duplicate order.
Plan for stale prices, rate limiting, disconnections, partial fills, market closures, rejected orders and provider maintenance. Define risk controls that continue to work when a downstream API or network is unavailable.
API Limits, Fees and Practice Environments
Rate limits and streaming limits are specific to a provider and endpoint. For example, OANDA’s v20 documentation publishes its own limits; those numbers must not be generalized to another broker. Confirm market-data subscriptions, order limits, usage restrictions and any hosting or connectivity charges.
A practice environment is useful for checking request formats and application behavior. It does not establish live liquidity, execution quality, price parity or account eligibility.
API Due-Diligence Checklist
| Account and entity | Identify the contracting company, account type and allowed products. |
|---|---|
| Capabilities | Confirm market data, order types, account reads, amendments and cancellations separately. |
| Security | Review authentication, credential scope, rotation, storage and revocation. |
| Reliability | Read rate limits, service status, retry guidance, reconciliation and outage behavior. |
| Cost and rights | Check data entitlements, API fees, redistribution limits and automation terms. |